The current study presents a uniaxial compression testing of <110>-oriented single-crystalline Iridium micropillars with diameters ranging from 1000 nm to 7400 nm fabricated by focused-ion-beam (FIB). The tests were performed on a nanomechanical instrument. The results reveal that the yield strength of micropillars follow a power law depending on diameter, as reported in other face-centered cubic (FCC) metals. Unlike the mechanical behavior of bulk Iridium when performing uniaxial compression, the flow stress at micro- and nano-scale is found to increase with a decreasing of micropillar diameter, which is attributed to a size-dependent effect. Moreover, the plastic deformation shows a periodical jerky and strain bursts. This work mainly focused on the rate of strain bursts and the sensitivity of strain rate in Iridium micropillars under uniaxial compression. The experiments also indicate that the displacement jumps increase with the extending of durations and micropillar diameter. In addition, the strain rate sensitivity (SRS) index m increases with a decreasing diameter of Iridium micropillar.